Multiple monitors with i3 window manager

I just started using i3 (version 4.17.1), and cannot figure out how to get it working with 2 monitors. I am running Ubuntu 20.04, and when I log into gnome, it utilizes them both. My research suggested that I needed to run the following command. HDMI-0 is my main monitor (that's the one that is working), and DVI-1-0 is my second monitor (not working).

$ xrandr --output DVI-1-0 --auto --right-of HDMI-0

That didn't do anything as far as I can tell. I ran xrandr in both gnome and i3, to hopefully help me troubleshoot. Their content, along with my i3 config file is below. I can see differences, but don't have enough experience to know what to make of them.

xrandr from gnome:

Screen 0: minimum 8 x 8, current 3200 x 1080, maximum 32767 x 32767
DVI-D-0 disconnected (normal left inverted right x axis y axis)
HDMI-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 575mm x 323mm
   1920x1080     60.00*+  60.00    59.94    50.00    23.98    60.05    60.00    50.04  
   1680x1050     59.95  
   1366x768      59.79  
   1280x1024     60.02  
   1280x960      60.00  
   1280x800      59.81  
   1280x720      60.00    59.94    50.00  
   1024x768      60.00  
   800x600       60.32    56.25  
   720x576       50.00  
   720x480       59.94  
   640x480       59.94    59.93  
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-1-0 disconnected (normal left inverted right x axis y axis)
HDMI-1-0 disconnected (normal left inverted right x axis y axis)
DVI-1-0 connected 1280x720+1920+0 (normal left inverted right x axis y axis) 373mm x 209mm
   1280x720      59.86*+
   1280x1024     60.02  
   1280x960      60.00  
   1152x864      59.97  
   1152x720      59.97  
   1024x768      60.00  
   800x600       60.32  
   640x480       59.94  
   720x400       70.08  
  1280x1024 (0x1c9) 108.000MHz +HSync +VSync
        h: width  1280 start 1328 end 1440 total 1688 skew    0 clock  63.98KHz
        v: height 1024 start 1025 end 1028 total 1066           clock  60.02Hz
  1280x960 (0x1ca) 108.000MHz +HSync +VSync
        h: width  1280 start 1376 end 1488 total 1800 skew    0 clock  60.00KHz
        v: height  960 start  961 end  964 total 1000           clock  60.00Hz
  1024x768 (0x1cf) 65.000MHz -HSync -VSync
        h: width  1024 start 1048 end 1184 total 1344 skew    0 clock  48.36KHz
        v: height  768 start  771 end  777 total  806           clock  60.00Hz
  800x600 (0x1d0) 40.000MHz +HSync +VSync
        h: width   800 start  840 end  968 total 1056 skew    0 clock  37.88KHz
        v: height  600 start  601 end  605 total  628           clock  60.32Hz
  640x480 (0x1d4) 25.175MHz -HSync -VSync
        h: width   640 start  656 end  752 total  800 skew    0 clock  31.47KHz
        v: height  480 start  490 end  492 total  525           clock  59.94Hz

xrandr from i3

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
DVI-D-0 disconnected primary (normal left inverted right x axis y axis)
HDMI-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 575mm x 323mm
   1920x1080     60.00*+  60.00    59.94    50.00    23.98    60.05    60.00    50.04  
   1680x1050     59.95  
   1366x768      59.79  
   1280x1024     60.02  
   1280x960      60.00  
   1280x800      59.81  
   1280x720      60.00    59.94    50.00  
   1024x768      60.00  
   800x600       60.32    56.25  
   720x576       50.00  
   720x480       59.94  
   640x480       59.94    59.93  
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-1-0 disconnected (normal left inverted right x axis y axis)
HDMI-1-0 disconnected (normal left inverted right x axis y axis)
DVI-1-0 connected (normal left inverted right x axis y axis)
   1280x720      59.86 +
   1280x1024     60.02  
   1280x960      60.00  
   1152x864      59.97  
   1152x720      59.97  
   1024x768      60.00  
   800x600       60.32  
   640x480       59.94  
   720x400       70.08  
  1280x1024 (0x1c9) 108.000MHz +HSync +VSync
        h: width  1280 start 1328 end 1440 total 1688 skew    0 clock  63.98KHz
        v: height 1024 start 1025 end 1028 total 1066           clock  60.02Hz
  1280x960 (0x1ca) 108.000MHz +HSync +VSync
        h: width  1280 start 1376 end 1488 total 1800 skew    0 clock  60.00KHz
        v: height  960 start  961 end  964 total 1000           clock  60.00Hz
  1024x768 (0x1cf) 65.000MHz -HSync -VSync
        h: width  1024 start 1048 end 1184 total 1344 skew    0 clock  48.36KHz
        v: height  768 start  771 end  777 total  806           clock  60.00Hz
  800x600 (0x1d0) 40.000MHz +HSync +VSync
        h: width   800 start  840 end  968 total 1056 skew    0 clock  37.88KHz
        v: height  600 start  601 end  605 total  628           clock  60.32Hz
  640x480 (0x1d4) 25.175MHz -HSync -VSync
        h: width   640 start  656 end  752 total  800 skew    0 clock  31.47KHz
        v: height  480 start  490 end  492 total  525           clock  59.94Hz

.config/i3/config

# This file has been auto-generated by i3-config-wizard(1).
# It will not be overwritten, so edit it as you like.
#
# Should you change your keyboard layout some time, delete
# this file and re-run i3-config-wizard(1).
#

# i3 config file (v4)
#
# Please see https://i3wm.org/docs/userguide.html for a complete reference!

set $mod Mod4

# Font for window titles. Will also be used by the bar unless a different font
# is used in the bar {} block below.
font pango:monospace 8

# This font is widely installed, provides lots of unicode glyphs, right-to-left
# text rendering and scalability on retina/hidpi displays (thanks to pango).
#font pango:DejaVu Sans Mono 8

# The combination of xss-lock, nm-applet and pactl is a popular choice, so
# they are included here as an example. Modify as you see fit.

# xss-lock grabs a logind suspend inhibit lock and will use i3lock to lock the
# screen before suspend. Use loginctl lock-session to lock your screen.
exec --no-startup-id xss-lock --transfer-sleep-lock -- i3lock --nofork

# NetworkManager is the most popular way to manage wireless networks on Linux,
# and nm-applet is a desktop environment-independent system tray GUI for it.
exec --no-startup-id nm-applet

# Use pactl to adjust volume in PulseAudio.
set $refresh_i3status killall -SIGUSR1 i3status
bindsym XF86AudioRaiseVolume exec --no-startup-id pactl set-sink-volume @DEFAULT_SINK@ +10% && $refresh_i3status
bindsym XF86AudioLowerVolume exec --no-startup-id pactl set-sink-volume @DEFAULT_SINK@ -10% && $refresh_i3status
bindsym XF86AudioMute exec --no-startup-id pactl set-sink-mute @DEFAULT_SINK@ toggle && $refresh_i3status
bindsym XF86AudioMicMute exec --no-startup-id pactl set-source-mute @DEFAULT_SOURCE@ toggle && $refresh_i3status

# Use Mouse+$mod to drag floating windows to their wanted position
floating_modifier $mod

# start a terminal
bindsym $mod+Return exec i3-sensible-terminal

# kill focused window
bindsym $mod+Shift+q kill

# start dmenu (a program launcher)
bindsym $mod+d exec dmenu_run
# There also is the (new) i3-dmenu-desktop which only displays applications
# shipping a .desktop file. It is a wrapper around dmenu, so you need that
# installed.
# bindsym $mod+d exec --no-startup-id i3-dmenu-desktop

# change focus
bindsym $mod+j focus left
bindsym $mod+k focus down
bindsym $mod+l focus up
bindsym $mod+semicolon focus right

# alternatively, you can use the cursor keys:
bindsym $mod+Left focus left
bindsym $mod+Down focus down
bindsym $mod+Up focus up
bindsym $mod+Right focus right

# move focused window
bindsym $mod+Shift+j move left
bindsym $mod+Shift+k move down
bindsym $mod+Shift+l move up
bindsym $mod+Shift+semicolon move right

# alternatively, you can use the cursor keys:
bindsym $mod+Shift+Left move left
bindsym $mod+Shift+Down move down
bindsym $mod+Shift+Up move up
bindsym $mod+Shift+Right move right

# split in horizontal orientation
bindsym $mod+h split h

# split in vertical orientation
bindsym $mod+v split v

# enter fullscreen mode for the focused container
bindsym $mod+f fullscreen toggle

# change container layout (stacked, tabbed, toggle split)
bindsym $mod+s layout stacking
bindsym $mod+w layout tabbed
bindsym $mod+e layout toggle split

# toggle tiling / floating
bindsym $mod+Shift+space floating toggle

# change focus between tiling / floating windows
bindsym $mod+space focus mode_toggle

# focus the parent container
bindsym $mod+a focus parent

# focus the child container
#bindsym $mod+d focus child

# Define names for default workspaces for which we configure key bindings later on.
# We use variables to avoid repeating the names in multiple places.
set $ws1 "1"
set $ws2 "2"
set $ws3 "3"
set $ws4 "4"
set $ws5 "5"
set $ws6 "6"
set $ws7 "7"
set $ws8 "8"
set $ws9 "9"
set $ws10 "10"

# switch to workspace
bindsym $mod+1 workspace number $ws1
bindsym $mod+2 workspace number $ws2
bindsym $mod+3 workspace number $ws3
bindsym $mod+4 workspace number $ws4
bindsym $mod+5 workspace number $ws5
bindsym $mod+6 workspace number $ws6
bindsym $mod+7 workspace number $ws7
bindsym $mod+8 workspace number $ws8
bindsym $mod+9 workspace number $ws9
bindsym $mod+0 workspace number $ws10

# move focused container to workspace
bindsym $mod+Shift+1 move container to workspace number $ws1
bindsym $mod+Shift+2 move container to workspace number $ws2
bindsym $mod+Shift+3 move container to workspace number $ws3
bindsym $mod+Shift+4 move container to workspace number $ws4
bindsym $mod+Shift+5 move container to workspace number $ws5
bindsym $mod+Shift+6 move container to workspace number $ws6
bindsym $mod+Shift+7 move container to workspace number $ws7
bindsym $mod+Shift+8 move container to workspace number $ws8
bindsym $mod+Shift+9 move container to workspace number $ws9
bindsym $mod+Shift+0 move container to workspace number $ws10

# reload the configuration file
bindsym $mod+Shift+c reload
# restart i3 inplace (preserves your layout/session, can be used to upgrade i3)
bindsym $mod+Shift+r restart
# exit i3 (logs you out of your X session)
bindsym $mod+Shift+e exec "i3-nagbar -t warning -m 'You pressed the exit shortcut. Do you really want to exit i3? This will end your X session.' -B 'Yes, exit i3' 'i3-msg exit'"

# resize window (you can also use the mouse for that)
mode "resize" {
        # These bindings trigger as soon as you enter the resize mode

        # Pressing left will shrink the window’s width.
        # Pressing right will grow the window’s width.
        # Pressing up will shrink the window’s height.
        # Pressing down will grow the window’s height.
        bindsym j resize shrink width 10 px or 10 ppt
        bindsym k resize grow height 10 px or 10 ppt
        bindsym l resize shrink height 10 px or 10 ppt
        bindsym semicolon resize grow width 10 px or 10 ppt

        # same bindings, but for the arrow keys
        bindsym Left resize shrink width 10 px or 10 ppt
        bindsym Down resize grow height 10 px or 10 ppt
        bindsym Up resize shrink height 10 px or 10 ppt
        bindsym Right resize grow width 10 px or 10 ppt

        # back to normal: Enter or Escape or $mod+r
        bindsym Return mode "default"
        bindsym Escape mode "default"
        bindsym $mod+r mode "default"
}

bindsym $mod+r mode "resize"

# Start i3bar to display a workspace bar (plus the system information i3status
# finds out, if available)
bar {
        status_command i3status
}

workspace 1 output HDMI-0
workspace 2 output DVI-1-0

In order to tell i3 how to organise your displays, you need to run the xrandr command from within your config file ~/.config/i3/config which it will load from when you login.

In your case, you need to put something like the following line in the above config file:

exec --no-startup-id xrandr --output DVI-1-0 --auto --right-of HDMI-0 &

These two lines in your config file:

workspace 1 output HDMI-0
workspace 2 output DVI-1-0

only tell i3 to put the virtual workspace named "1" on the HDMI display and "2" on the DVI display and does nothing for actually configuring the display properties.

I made a script that automates several monitors. You just have to run the command:

./screenz -p

to automatically connect to an output connect.

Or,

you can run the commande:

./screenz -c

to see all the outputs connected and choose your monitor.

If you are intereste and you want to know more, the github link: https://github.com/Zarfir/Screenz